Burner comprising a pre-combustion chamber

Abstract

A gas burner for use in low-oxygen environments in which the oxygen concentration is insufficient to ensure complete combustion. The burner includes a central air supply that is annularly surrounded by a gas supply, thereby preventing the fuel from burning out with a delay in places where burn-out is detrimental to a system or plant.

Claims

1. A method for operating a calcinator in a plant for producing cement clinker, in which lime, as hot meal, is freed of carbon dioxide and converted into burnt line, the method comprising: providing a gas burner for use in an oxygen-impoverished environment, an oxygen concentration of which is insufficient for supporting a complete combustion, and, supplying methane-rich natural gas as a fuel to the gas burner wherein the burner has a central air supply pipe which is annularly encompassed by a gas supply pipe, wherein the air supply pipe is dimensioned such that a sub-stoichiometric combustion takes place in the burner, and, wherein the fuel is conditioned as a result of the sub-stoichiometric combustion such that a complete burnout takes place under the oxygen-impoverished environment in the calcinator in the presence of carbon dioxide and hot meal, wherein, in a region of a mixing of fuel and air, an annularly disposed group of nozzles, forming a spiral vortex, is arranged, which mix the fuel with the air.

2. The method as claimed in claim 1, further comprising: providing a control device in the form of a throttle valve, which, by an adjustment of the supplied air flow and fuel flow, sets an air/fuel ratio λ to a value of 0.05 to 0.3, wherein the control device, by means of a closed-loop control device with a control loop, sets the desired λ value via at least one of a measured temperature in the combustion chamber or a spectrometrically measured gas concentration.

3. The method as claimed in claim 1, further comprising: providing at least one additional pilot burner which, in the region of the combustion chamber, reliably ignites the mixture of injected fuel and oxidation means.

4. The method as claimed in claim 1, wherein inner walls of the gas burner have at least one air suction nozzle, by means of which, sucked-in ambient air flows into the gas burner in the region of the walls of said burner and, as a result, cools the inner walls of the gas burner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention is explained in more detail with reference to the following FIGURE. In the drawing:

[0015] The FIGURE shows a vertical cross section through a burner according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Shown in the FIGURE is a vertical section through a combustion chamber 1 according to the invention in which the combustible gas 2 is mixed with an oxidation means 3, preferably hot tertiary air from the clinker cooler or kiln flue gas with sufficient residual oxygen, and substoichiometrically combusted. In this case, the aim in nominal operation is an air/fuel ratio λ of 0.05-0.3 which, depending on the fuel quantity which is required for the calcination process, can be adjusted by controlling the inflow rate of the oxidation means 3 by means of a throttle valve 10. The reactive and combustible gas mixture forming in the combustion chamber 1 can then burn out in the calcinator interior space 9 with the main part of the tertiary air from the clinker cooler and the residual oxygen of the kiln flue gas.

[0017] For the mixing of oxidation means 3 and combustible gas 2 use is made of an injector 4 in which, as a result of flow velocity of the combustible gas 2, the oxidation means 3 is sucked into the reaction chamber. This injector 4 can be arranged according to the invention as an annular gap, a nozzle ring or even be swirled, i.e., set at a tangent to the longitudinal axis.

[0018] If the temperature of the oxidation means 3 should not be sufficient for a reliable ignition, the reaction can be initiated by means of a suitable pilot burner 5, alternatively by means of an electric ignition device. For monitoring the reaction, a visual flame monitor 6 or even a thermoelement 11 can be used.

[0019] The wall of the combustion chamber 1 and of the supply pipe 7 for the oxidation means 3 can be protected against high temperatures and reaction products by means of suitable fireproof materials 12, 13 or even by means of a film consisting of sucked-in ambient air 14.

[0020] As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.